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Representing Intonational Variation

Julia Hirschberg

CS 4706

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Today

• How can we represent meaningful speech variation so we can compare utterances? assign in TTS?– Expanded vs. compressed pitch range?– Louder vs. softer speech?– Faster vs. slower speech?– Differences in intonational prominence?– Differences in intonational phrasing?– Differences in pitch contours?

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Joseph Steele, 1775

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Language Learning Approaches

• A simpler approach– / IS it INteresting /– / d’you feel ANGry? /– / WHAT’S the PROBlem? / (McCarthy,

1991:106)• How much variation do we need to capture?

– How detailed?– Continuous or categorical features?– If categorical, what are the possible classes?

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How Do We Decide?

•Auditory:

– Language teachers: what representations can learners understand

•Acoustic:

– Examine the speech signal for critical vs. accidental variation

•Experimental approaches

– Identify potential meaningful variation

– Design production or perception studies to test

– E.g. what does a contour mean?

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Intonation Models

• Superpositional models (Fujisaki 1983, Möbius et al. 1993): acoustic/physiological

• Linear or Tone sequence models

– British school (Kingdon ’58, O’Connor & Arnold ’73, Cruttenden ’97): based on auditory analysis

– American School (Pierrehumbert ’80, ToBI): mainly acoustic analysis

– Dutch school (‘t Hart, Collier and Cohen 1990): perceptual data

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Superpositional models

• Pitch pattern of intonation modeled with two components: phrase component and accent component.

• Phrase has basic shape, and pitch movements for individual accents are superimposed over basic shape:

plus

=Apples, oranges and tomatoes

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Lily and Rosa thought this was divine.Prince William was gorgeous and he was looking for a bride.They dreamed of wedding bells.

• Declination: downtrend in f0 over the course of an utterance

• Successful in speech synthesis for languages like Japanese (little variation in accent type, e.g.)

Good for modeling utterance-level trends

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Disadvantages

• Disadvantages– Too rigid: All contours must be modeled with

an accent and a phrase component – Many SAE contours cannot be captured easily

• Cannot distinguish prominence types• Cannot capture differences in phrase endings

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– No account of different accent types, or variations in phrase endings

– No notation system which allows users to share observations from large speech corpora or to compare contours

– Used primarily for synthesis

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Tone Sequence Models

• Intonation generated from sequences of categorically different, phonologically distinctive tones

• Basic unit of intonational description: intonation phrase (tone unit, breath group)– Delimited by pauses, phrase-final lengthening, pitch

• Syllables may be stressed or accented – Accent aligned with primary stress -- telephone– Indicated by F0, duration, intensity, voice quality

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British School

JOHN’s never BEEN to Jamaica

Prenuclear accent unit Nuclear accent unit

But

Prehead

Stressed syllable

‘Head’ ‘Nucleus’

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Six nuclear choices in English

Ja maic

falling

a ic

rising

Ja maa

a c

rising-falling

iJa m a

falling-rising

Ja maica

Rising-falling-rising

a ciJa m aalevel

Ja maica

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The American School

• American school-type models make a distinction between accents (what makes a particular word prominent) and boundary tones (how a phrase ends)

• Autosegmental metrical or two-tone models

• Only two tones, which may be combined

– H = high target

– L = low target

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Pierrehumbert 1980

• Contours = pitch accents, phrase accents, boundary tones

Pitch Accents*

Phrase Accents*

Boundary Tone

H* L*

L*+H L+H*

H*+L H+L*

L- H- L% H%

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Price, Ostendorf et al

• Break indices: degree of juncture between words

• 0 8 (none to ‘a lot’)– What I’d like is a nice roast beef sandwich.

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To(nes and)B(reak)I(ndices)

• Developed by prosody researchers in four meetings over 1991-94

• Putting Pierrehumbert ’80 and Price, Ostendorf, et al together

• Goals:

– devise common labeling scheme for Standard American English that is robust and reliable

– promote collection of large, prosodically labeled, shareable corpora

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• ToBI standards also proposed for Japanese, German, Italian, Spanish, British and Australian English,....

• Minimal ToBI transcription:

– Recording of speech

– F0 contour

– ToBI tiers: • orthographic tier: words

• break-index tier: degrees of junction (Price et al ‘89)

• tonal tier: pitch accents, phrase accents, boundary tones (Pierrehumbert ‘80)

• miscellaneous tier: disfluencies, non-speech sounds, etc.

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Sample ToBI Labeling

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• Online training material,available at: http://anita.simmons.edu/~tobi/index.html

• Evaluation– Good inter-labeler reliability for expert and

naive labelers: 88% agreement on presence/absence of tonal category, 81% agreement on category label, 91% agreement on break indices to within 1 level (Silverman et al. ‘92,Pitrelli et al ‘94)

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Pitch Accent/Prominence in ToBI

• Which items are made intonationally prominent and how: tonal targets/levels not movement

• Accent type:

– H* simple high(declarative)– L* simple low (ynq)– L*+H scooped, late rise (uncertainty/

incredulity)– L+H* early rise to stress (contrastive focus)– H+!H* fall onto stress (implied familiarity)

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•Downstepped accents:

•!H*,

•L+!H*,

•L*+!H

•Degree of prominence:within a phrase: HiF0 (~nuclear accent)

across phrases ??

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Prosodic Phrasing in ToBI

• ‘Levels’ of phrasing:

– intermediate phrase: one or more pitch accents plus a phrase accent, H- or L-

– intonational phrase: 1 or more intermediate phrases + boundary tone, H% or L%

• ToBI break-index tier

– 0 no word boundary– 1 word boundary

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– 2 strong juncture with no tonal markings

– 3 intermediate phrase boundary

– 4 intonational phrase boundary

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L*+H

L*

H*

H-H%H-L%L-H%L-L%

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H* !H*

H+!H*

L+H*

H-H%H-L%L-H%L-L%

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• ToBI exercises• NB: you will be submitting these exercises for

the take-home part of the midterm, so save them!

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Next Class

• Predicting prosodic assignments from text